SSRS – Cannot Create Subscription for Report Using SSAS as Data Source

Depending on what type/volume of data you are reporting on, SSAS can possibly make it easier. I would not take that as a blanket statement. The decision to generate reports off of a relational or dimensional database should be made on a case by case basis.

Keep in mind that the development required to build an OLAP database around a subject area is far more time consuming than building a single report (or even several).

The benefits of building out an OLAP database are huge in return. In many cases, your users can connect directly to it with excel and generate their own reports. This eases the SSRS development requirements on IT.

At the end of the day, there are many factors that would contribute to answering your question. There is simply not a one size fits all solution.

Depending on the version of Report Builder, you can only build from a single data source. I'm pretty sure this is still the case with SQL Server 2008R2, although Report Builder 3 can consume data directly from a database without needing a report model, although you need to build data sets using the individual connections and I don't think you can group items from different data sets by a common value.

You can do this gouping with SSRS (see this article for an overview), although I can't see an obvious way to do it in RB3. This article indicates that you can't nest items based on different data sets, so it's looking like common rollups aren't possible in RB3.